This invention relates to dental imaging devices and their use in dental radiology and dental practice. More specifically, this invention relates to producing analog and digital images from positive images on x-ray film using a device comprising a tank having a window with at least one camera movably attached and at least one monitor, whereby capture from x-ray film of positive video images that can readily be displayed on video monitors is broadly enabled, and wherein the functional utility, ease of use, and wide applicability of the device in dental practice constitutes progress in science and the useful arts. Furthermore, the present invention teaches processes for the use of the device in dental diagnosis and practice.
Dentistry is the treatment and care of the teeth and associated oral structures. In addition to general practice, currently there are eight recognized specialties within the field of dentistry. These specialties include periodontics, endodontics, orthodontics, prosthodontics, pedodontics, oral pathology/oral medicine, oral and maxillofacial surgery, and dental public health. Each of these specialties has a designated function for the care of the patient. A periodontist is responsible for treating periodontal (gum) disease. This treatment may range from regular maintenance visits with a hygienist to surgical procedures designed to save teeth. An endodontist's responsibilities include aiding in diagnosis of tooth pain and performing root canals and surgical procedures to treat the nerve tissue to save teeth. An orthodontist diagnoses and treats occlusal discrepancies and malaligned teeth with braces and orthodontic appliances. A prosthodontist specializes in preparing crowns, bridges, dentures, and implants. Prosthodontists can be especially helpful for complicated cases. Pedodontists only treat children and young adults (usually until about 18 years old). An oral pathologist is trained in diagnosis and treatment of pathological conditions affecting the tissues of the oral cavity. Most people associate oral surgeons with the extraction of wisdom teeth. In some cases, this may be the oral surgeon's "bread and butter," but oral surgeons are trained in many other areas of oral and facial surgery. In fact, several oral surgery programs offer combined dental and medical degrees (DDS or DMD and MD).
Dentistry is mainly concerned with tooth decay, disease of the supporting structures such as the gums, and faulty positioning of the teeth. Like medicine, dentistry has ancient roots, and the Etruscans already made excellent crowns and bridges in the seventh century BC. However, one of the greatest advances in dental practice, the use of diagnostic x-rays, was not discovered until 1895. In many situations in a dental office it is very desirable for the dentist to view a radiographic image of one or more teeth quickly on a video or computer monitor, both for time savings, and to show the patient an image of his/her tooth.
Normally, patients seek the care of their general practitioner dentist for a dental problem. Regardless of the particular symptoms which lead a patient to seek treatment by a dentist, the first step that the dental practitioner takes is to begin a diagnosis of the pathology underlying the symptoms, so that a course of treatment can be determined. Among the most powerful techniques that the dentist has available to make such a diagnosis is the process of radiological imaging (x-ray imaging).
Film based radiographic imaging (x-ray films) is the most common imaging modality in current dental practice. Such an image is of value in several ways other than diagnosis and treatment planning. Thus, such images are important for informing other dental specialists to whom the patient may be referred by the primary practitioner, for clinical management documentation to record the progress of the treatment, for office management documentation, such as documenting insurance billing, and for discussions to apprise the patient of his or her condition and treatment. Each of these applications requires close examination of the x-ray image, and some applications require that the image be transported from one site to another. Thus, it is clear that methods to facilitate the viewing and transport of dental x-ray images are of major importance in dental diagnosis and practice.
Over the last 100 years, radiographic film (x-ray film) has gone through several evolutionary changes to improve its resolution and dynamic range, reduce fogging, and increase speed (hence requiring less x-ray radiation). Through years of clinical usage, film based radiography has become the acceptable technique and a gold standard for clinical acceptance of alternative radiographic imaging systems. Today, more than 95% of dentists using radiography employ x-ray films.
The American Dental Association (ADA) has specific recommendations for radiographs (x-rays), although dentists are also encouraged to use their professional judgment based on the health and dental history of the patient. For an adult patient who has several restorations and might be cavity-prone, yearly radiographs are recommended. The type of radiograph that aids in diagnosis of decay or bone loss between teeth is called a bitewing x-ray. Many dentists consider a reasonable amount of dental radiography to include a full mouth set of radiographs every 5-7 years; bitewing radiographs every 1-2 years, and any additional films necessary to aid in the diagnosis of a particular condition. One reason to take bitewing radiographs is to check between the teeth because this area cannot be seen during a dental examination. Bitewing x-rays help reveal problems while they are small, before they cause any symptoms.
The dentist also checks the bone level adjacent to the teeth, examines the roots and nerves of teeth, checks the position and development of teeth, diagnoses lesions such as cysts or tumors, assesses damage when trauma occurs, and diagnoses and monitors periodontal disease. Even if a patient has a healthy mouth, these radiographs can prove to be very beneficial for future comparison--especially if a dental emergency or condition should arise. Thus, dental radiographs are invaluable aids in diagnosing, treating, and maintaining dental health in both children and adults.
The exposure time for dental radiographs is minimal. The risk of ill effects from exposure to x-rays is essentially non-existent in the case of dental x-rays. A comparison of radiation doses from radiography and background radiation (atmospheric, cosmic, etc. radiation) can be made with the mean active bone marrow dose. Researchers compared whole-body bone marrow dose from background radiation to the data from radiographic examinations. They concluded that if a person in an average location in the United States were to receive a full-mouth intraoral periapical and panoramic examination every four months for the rest of his life, he or she would incur only the same risk as a person living in Denver who was not exposed to dental radiography. Denver is exposed to more atmospheric radiation, due to the high elevation of this city.
After x-rays are obtained in the office of the primary care dentist or the dental specialist, the dentist must examine them in order to diagnose the dental ailment to be treated, as already mentioned. Thus, the dentist may identify dental decay, or caries, by noting dark areas on the x-ray. As previously noted, the dentist also checks the bone level adjacent to the teeth, examines the roots and nerves of teeth, checks the position and development of teeth, diagnoses lesions such as cysts or tumors, assesses damage when trauma occurs, and diagnoses and monitors periodontal disease. In order to do this, the dentist must carefully examine the x-ray image. The conventional way in which this is done is to clip the film to a source of even, diffused light, often called a "lightbox".
Alternatively, the film is simply held up to a source of light, such as a lamp. The abnormal areas in the teeth can then be viewed and noted. The patient also can view these areas as pointed out by the dentist. However, inasmuch as only a life-size view of the teeth is seen in this manner, it is often difficult to discern the areas of pathology using this technique. Accordingly, a need has existed for viewing x-ray images in enlarged format, but simple means to do this have not been forthcoming.
Moreover, in the past, dentists have had to rely on developing dental x-ray film in their offices in order to have rapid access to the images while treating the patient. Automatic and manual dental x-ray film processors heretofore known require about six minutes to produce a single dental x-ray film image ready for mounting. This delay undesirably requires the patient to sit alone in the treatment room for some period of time, undesirably prolongs the time the patient must spend in the dental office, and undesirably reduces the number of patients per day that the dentist can treat.
Variations on the known film processing systems have not been forthcoming, despite recent developments in the technology related to film processing. Even though x-ray films are used extensively in dental practice, prior art film processing devices, dental film based products, or methods available to dentists have not adequately addressed the required need for accelerated rapid imaging of dental x-ray film as set forth below.
By way of background, attention is called to the following. Prior patents have described apparatus for the capture of an image from negative photographic film while it is being processed in an automatic roller processor. In U.S. Pat. No. 5,101,286 Patton captures the film image in the bleach tank or just after the bleach tank of an automatic roller processor. It is then digitized for viewing and evaluation. This apparatus is used to determine if a photographic print from the negative in question should be made. In U.S. Pat. No. 5,432,579 Tokuda describes the image capture from a film negative in an automatic roller film processor wash tank. The image is then sent to a printer/processor where photoprints are made.
The above two patents differ from the present invention in that they both are involved with the capture of an image from film negatives. They are both entirely involved with photographic film. In U.S. Pat. No. 4,965,601 Canty describes a camera attached to a window in a reaction vessel. This vessel is used for chemical, food processing, metallurgical processes, and the like. None of these inventions are suitable for dentistry, nor are they commercially available or marketed to dentists.
By way of further background, attention is called to prior art methods and devices that have attempted to avoid the dental film processing delay by eliminating dental film altogether. One development to address this need that has appeared in recent years is that of digital dental imaging (digital radiography) using intraoral radiographic sensors based on charge-coupled devices (CCD). These are small x-ray sensors, comparable in size to an intraoral film. They are used in place of film and are linked directly to a computer. When an x-ray image is taken using these sensors, the image is not recorded on film, but instead is digitally recorded in the computer and displayed on a display device.
Current technology for creating a digital radiological image of a patients'teeth uses a sensor which is configured to be sensitive to x-rays. This sensor is electronically connected to a computer thence to a monitor and/or a printer. This sensor is placed in the patients'mouth behind the area to be x-rayed. An x-ray head is then aimed at the teeth in question. The x-ray is activated, radiation going through the teeth and onto the sensor. The sensor sends the image created to a computer. The computer then digitizes the image. Once it is digitized, it can then be sent to a printer for the production of a hard copy "picture". Alternatively, it can be sent to a video monitor. Because the image is digitized, it can be further enhanced for greater clarity. It can be zoomed in or out, inverted, contrasted with different intensities, or color switched, black to white, and white to black.
Another type of digital radiological apparatus uses a phosphorescent sensor, which is sensitive to x-rays and is electronically independent of the computer. This type of sensor is placed in the mouth of the patient, much like film. It is then radiated, and placed into a "reading" apparatus, which digitizes the image on the sensor. It can then be sent to a computer for viewing, storage, and alteration as desired by the operator.
A serious disadvantage of digital radiography is its high cost. While few dentists expect miraculous revenue growth from implementing a new method of taking x-rays, most expect at least an adequate return of investment (ROI). Persistent concerns about ROI of digital radiography has led to a major slow down in the spread of the technology in the United States, and even today 97% of dentists do not use this technology. Clearly, there is a need for a device that can produce high quality video images, high quality hard copy images, and high quality radiographic film images. A technically simpler device than that used by current digital radiology would make the cost of purchase of such a device more accessible to dental practitioners. The present invention fulfills these needs.
A number of advantages have been attributed to the use of digital dental imaging, but it is pertinent to point out that in every case these advantages have either not been realized in a practical sense, or are equally well provided by the present invention in a far more cost effective manner. These unrealized advantages are discussed in the following paragraphs.
1. Dentist, Patient, and Specialist Are All Able to View Enlarged Digital Image on Monitor. This is one of the principal advantages claimed for digital imaging. However, the present invention accomplishes exactly the same objective at far lower cost. Furthermore, at the present time only about 3% of dental professionals have the expensive equipment required to receive and display digital images, so there is little chance of exploiting this supposed advantage. Again, dental professionals can employ the present invention to accomplish this objective at far lower cost.
2. Ease of Sending Images Electronically. Electronic transmission to insurance companies or other professionals is a distinct advantage, but is possible only if they have the capability to receive the images. At the present time only about 3% of dental professionals have such equipment so there is little chance of exploiting this supposed advantage.
3. Reduced Exposure Time. Although the exposure time is about 50% less with digital imaging compared to traditional radiographs, x-ray exposure is not a significant risk in normal dental x-ray practice, as already discussed. Yet, unlike film, where a new film is used for every x-ray exposure, with digital imaging the x-ray sensor is used repeatedly. After a number of exposures, the sensitivity of the sensor is so degraded that it may require a longer exposure than film. In addition, digital radiographs cover a smaller area than film radiographs; so more images may be required, in some cases resulting in an increased exposure time.
4. Processing of Film is Eliminated. The elimination of film processing has been cited as an advantage of digital radiography.
5. Image Alteration Although digital imaging does not increase diagnostic information, in principle it can be altered to make valuable diagnostic information more evident. However, this potential advantage of digital imaging is very difficult to demonstrate. For example, although alteration of the image may make visualization of cavities better; the main problem is that it is not usually clear which operations are applicable for such a diagnostic task, and these contrast enhancement operations differ among the various manufacturers. The result is that dentists rarely use this capability.
6. Disk Storage of Images. This supposed advantage of digital imaging, which avoids the need to store films, creates a disk capacity problem in a busy dental office. This requires the constant upgrading of the disk storage facility, a far more expensive task than providing film storage space.
In addition, sensor based digital radiography imaging systems have disadvantages not present in film based systems. These problems are the following:
1. The cable connection to the sensors is relatively fragile and may be broken during usage. PA1 2. Images derived from electronic sensors or fluorescent cards have resolutions of only about 360,000 pixels, whereas film has an unrivaled resolution of 18,000,000 pixels. On a display monitor, electronic sensors or fluorescent cards have a resolution of 7-10 lines/millimeter whereas film produces a resolution of 15 lines/millimeter. PA1 3. Electronic and fluorescent sensor cards are typically thicker than film and difficult to bend as can be done with a piece of film. This may cause great discomfort to the patient. They do not fit easily in the mouth of the patient, and the placement and removal process may scratch the delicate tissue lining the mouth and gums. PA1 4. The price of sensors is approximately $ 3000-6000 per unit, versus the price of a film and holder of approximately $ 0.20. PA1 5. Electronic and fluorescent sensor cards cannot be sterilized and must be reused with only a plastic bag or "baggie" to protect the patient. PA1 6. The quality of the image produced by the reused sensors progressively deteriorates as the sensor ages, whereas a fresh film is used for each exposure. PA1 7. Because digital images can easily be modified, they are not acceptable evidence in malpractice legal proceedings. Film negatives are the standard of evidence acceptable in a court of law. PA1 8. The hard copy produced is also of poor quality. It is difficult for the practitioner to see much detail. Film radiographs are far superior in quality and resolution. PA1 9. Digital radiological imaging is advantageous for only one or two films. It is not possible to take a full set of radiographs, eighteen to twenty-two films, (or even four bitewing films) and view them clearly at the same time on a computer monitor. Each individual radiograph is too small when all are viewed as a whole, considering the comparatively poor quality of digital imaging. It is necessary to be constantly zooming in and out to different individual pictures. When a dentist has a full set of "film" radiographs in front of him, his or her eyes constantly scan from film to film to contrast and compare different areas, which greatly aids in making the diagnosis. This cannot be done when a full set of radiographs is on a computer screen. PA1 10. Ergonomically, the hard copies produced on the printer are extremely difficult to view and diagnose, when in groups of eighteen to twenty- two, and to store. Viewing the pictures is like viewing a stack of photographs. The bigger the stack, the more awkward the handling. Storing the hard copies in the patient charts, which must be done in case the computers hard disc breaks down or is destroyed, becomes cumbersome over time, because the stack of hard copies gets thicker and more cluttered. PA1 (a) to provide a device for producing video and digital images directly from dental radiographic film. PA1 (b) to provide a device for rapid access to enlarged dental images directly from dental radiographic film for purposes of dental diagnosis. PA1 (c) To provide a device that enlarges even minor or obscure evidence of dental pathology on dental radiographic film for purposes of dental diagnosis. PA1 (d) to provide a device which overcomes the drawbacks of the prior art by incorporating the advantages of film radiography such as low cost, sterilizability, patient comfort, constant sensitivity, and constant sensitivity with the convenience of viewability on a monitor. PA1 (e) to provide a device which overcomes the drawbacks of the prior art by making it possible for dentists, patients, and specialists to view enlarged positive radiographic images on a monitor at 15 lines/millimeter resolution using film as a source shortly after exposure. PA1 (f) to provide a device which overcomes the drawbacks of the prior art by making it possible for dentists to take a full set of radiographs, eighteen to twenty-two films, (or even four bitewing films) and rapidly view each film interchangeably on a computer monitor. PA1 (g) to provide a simple device that can produce high quality video images, high quality hard copy images, and high quality radiographic film images at a cost of purchase that is more accessible to dental practitioners. PA1 (h) a process is also taught whereby dental film radiographs are taken of a patient, processed to the positive stage and displayed using the device of the invention, and interpreted by a dentist to produce a diagnosis of the dental pathology of the patient.
Thus, although radiography is used commonly and extensively in dentistry, prior art visualization systems have not adequately addressed the need for enhanced visualization methods as set forth below. Advances in economically accessible enhanced radiograph viewing systems have not been forthcoming. While it has been known to enlarge digital images of radiographs with a cathode ray tube (CRT) monitor device, such disclosures have not adequately addressed the ROI constraints that must be met in order to secure widespread adoption of such systems.
In contradistinction to all of these imaging devices, the present invention embraces and finally addresses the clear need for a dental radiograph analog imaging device. Thus, as pioneers and innovators attempt to make dental imaging devices cheaper, more universally used, and of higher quality, none has approached same in combination with simplicity and reliability of operation, until the teachings of the present invention. It is respectfully submitted that other references merely define the state of the art or show the type of systems which have been used to alternately address those issues ameliorated by the teachings of the present invention. Accordingly, further discussions of these references has been omitted at this time due to the fact that they are readily distinguishable from the instant teachings to one of skill in the art.